alleryStart learning →What is distinctive about the walls of the pulmonary capillary network?
AThey carry a thick layer of elastic fibres
BThey are ringed by incomplete cartilage
CThey are very thin and lack smooth muscle
DThey are lined by ciliated columnar cells
Answer & Solution
Correct answer: C. They are very thin and lack smooth muscle
1. As the pulmonary arteries near the alveoli they become the pulmonary capillary network.
2. Those vessels are tiny, with very thin walls that lack smooth muscle fibres.
3. Thin walls are what allow the capillary wall to meet the alveolar wall and form the respiratory membrane.
4. Cartilage rings and ciliated columnar linings belong to conducting airways, not to capillaries.
_Source: OpenStax Anatomy and Physiology (CC BY 4.0), Ch 22 "The Respiratory System", section 22.2 The Lungs_
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